Penicillin-induced Epileptiform Activity Research Articles

Effects of intracortical microinjection of vitamin B12 on penicillin-induced epileptiform activity in rats

There are increasing studies indicating neuroprotective effects for vitamin B12. In the present study, the effect of intracortical microinjection of vitamin B12 was investigated on penicillin-induced epileptiform activity. We also examined the effects of intracortical microinjection of diazepam (a GABA-benzodiazepine receptor agonist) and flumazenil (a GABAbenzodiazepine receptor antagonist) to clarify the possible mechanism of vitamin B12. In urethane-anesthetized rats, epileptiform activity was induced by intracortical microinjection of penicillin (300 IU, 1.5 microL), and the number and amplitude of spike waves were analyzed using electroencephalographic (EEG) recordings. Intracortical microinjections of vitamin B12 at doses of 100 and 200 ng/site, diazepam at a dose of 200 ng/site and their ineffective doses (50 ng/site of vitamin B12 with 50 ng/site of diazepam) co-microinjection treatment significantly (P less than 0.05) reduced both the number and amplitude of spike waves. In addition, combined microinjection of effective doses of vitamin B12 (100 ng/site) and diazepam (200 ng/site) produced more antiepileptiform effect in comparison with their alone used doses. The antiepileptic effects induced by microinjection of vitamin B12 and diazepam at a same dose of 200 ng/site were prevented by the same site microinjection of 50 ng/site of flumazenil. The results showed antiepileptiform activities for vitamin B12 and diazepam AT the cerebral cortex level. A central GABA-benzodiazepine receptor complex-mediated mechanism might be involved in the antiepileptiform activity of vitamin B12.

The Effects of Erythropoietin on the Penicillin Induced Epileptiform Activity in Rats

The Effects of Erythropoietin on the Penicillin Induced Epileptiform Activity in Rats

Effect of levetiracetam on penicillin induced epileptic activity in rats.

The aim of this study was to investigate the effects of levetiracetam (LEV) on penicillin-induced epileptiform activity in rats. Penicillin was applied intracerebroventricularly (icv) at a dose of 500 IU to induce epileptiform activity. LEV was given intraperitoneally (ip) at doses of 20, 40, 80 mg/kg before penicillin injection. This agent reduced epileptiform activity by decreasing spike frequencies. The mean spike frequencies decreased significantly in all the LEV treated groups. There was no significant change in the spike amplitudes of the LEV groups compared with the control group. 40 mg/kg of LEV was determined as the most effective dose on reducing epileptiform activity. The results of this study suggest that LEV is an effective antiepileptic agent in penicillin-induced epilepsy.

The interaction between ghrelin and cannabinoid systems in penicillin-induced epileptiform activity in rats

The majority of experimental and clinical studies show that ghrelin and cannabinoids are potent inhibitors of epileptic activity in various models of epilepsy. A number of studies have attempted to understand the connection between ghrelin and cannabinoid signalling in the regulation of food intake. Since no data show a functional interaction between ghrelin and cannabinoids in epilepsy, we examined the relationship between these systems via penicillin-induced epileptiform activity in rats. Doses of the CB1 receptor agonist arachidonyl-2-chloroethylamide (ACEA) (2.5 and 7.5 µg), the CB1 receptor antagonist N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3 carboxamide (AM-251) (0.25 and 0.5 µg) and ghrelin (0.5 and 1 µg) were administered intracerebroventricularly (i.c.v.) 30 minutes after the intracortical (i.c.) application of penicillin. In the interaction groups, the animals received either an effective dose of ACEA (7.5 µg, i.c.v.) or a non-effective dose of ACEA (2.5 µg, i.c.v.) or effective doses of AM-251 (0.25, 0.5 µg, i.c.v.) 10 minutes after ghrelin application. A 1 µg dose of ghrelin suppressed penicillin-induced epileptiform activity. The administration of a 0.25 µg dose of AM-251 increased the frequency of penicillin-induced epileptiform activity by producing status epilepticus-like activity. A 7.5 µg dose of ACEA decreased the frequency of epileptiform activity, whereas a non-effective dose of ACEA (2.5 µg) did not change it. Effective doses of AM-251 (0.25, 0.5 µg) reversed the ghrelin's anticonvulsant activity. The application of non-effective doses of ACEA (2.5 µg) together with ghrelin (0.5 µg) within 10 minutes caused anticonvulsant activity, which was reversed by the administration of AM-251 (0.25 µg). The electrophysiological evidence from this study suggests a possible interaction between ghrelin and cannabinoid CB1 receptors in the experimental model of epilepsy.

Efficacy of dexamethasone on penicillin-induced epileptiform activity in rats: An electrophysiological study

Corticosteroids are extensively used in treatment of many diseases. In neurosurgery practice, dexamethasone (DEX) is commonly used particularly in cerebral edema secondary to brain tumors, head trauma, and central nervous system infections. There are some uncertainties surrounding the secure use of DEX in patients with epilepsy or seizures induced by diseases of the central nervous system such as head trauma and brain tumors. Despite its extensive use, the effect of DEX on epileptiform activity is unclear. In this study the effect of DEX on epileptiform activity was investigated in rats. The effects of 1, 3, and 10mg/kg DEX on epileptiform activity was compared with effects of antiepileptic drugs commonly employed in treatment of epilepsy, namely phenytoin (PHT) 50mg/kg and levetiracetam (LEV) 50mg/kg that were administered intraperitoneally for 1 week. All groups were administered intracortical penicillin (500IU) to induce epileptiform activity. DEX at the doses of 3mg/kg and 10mg/kg significantly reduced spike frequencies compared to the initial values. In conclusion, we think that DEX can effectively decrease the epileptiform activity.

Electrophysiological evidence on epileptiform activity enhanced by electrical stimulation of teeth in rats

The aim of this study was to evaluate the possible effects of electrical stimulation (ES) of tooth on penicillin-induced epileptiform activity in rats.Experiment was realized on 24 adult male Sprague Dawley rats. Rats were assigned three groups [stimulation group (SG), penicillin group (PG), and penicillin+stimulation group (PSG)]. In SG, ES was only applied. Ten pulses of electrical current were delivered to the teeth for a duration of 2 milliseconds at 1-second intervals from a stimulator. Currents were applied in the range of 40–240 μA with 40 μA steps. Electrocorticography (ECoG) recordings were taken before and after ES. In PG, ECoG recordings were taken before and during the injection of penicillin. In PSG, after epileptiform activity was induced, ES was applied and ECoG recordings were taken as in SG. All the data were analyzed with Student’s t test. Applied currents did not cause any epileptiform activity in SG. When the PSG was compared with the PG it was seen that the spike frequency of epileptiform activity increased in a statistically significant way after application of 240 μA (P < 0·05). On the other hand current application caused an increase in the spike amplitude of the PSG compared with the amplitude of the PG, but it was not statistically significant.We concluded that ES of tooth with high current can trigger epileptiform activity in rats. For this reason, further research is required to evaluate the effects of ES of tooth for pulp testing on epileptic human subjects and antiepileptic drug users.

Electrophysiological evidence for the anticonvulsant effect of alpha-lipoic acid via indirect antioxidant properties in BALB/c mice

Alpha-lipoic acid (alpha-LA) is a strong antioxidant whose effect on epilepsy has not been completely clarified yet. The present study was designed to investigate the effects of alpha-LA on epileptiform activity induced by penicillin in BALB/c mice.In the present study, 56 adult male BALB/c mice were divided into seven groups. Under urethane anesthesia, the mice were injected with intracortical (i.c.) 200 IU penicillin following craniotomy to start epileptiform activity. The effects of alpha-LA on epileptiform activity were examined through the intraperitoneal (i.p.) application of 25, 50, 100, 200, and 400 mg/kg doses. The electrophysiological data have demonstrated that alpha-LA at the 200 mg/kg dose showed an anticonvulsant effect by reducing penicillin-induced epileptiform activity. This effect obtained at the 200 mg/kg dose was determined to emerge 80 minutes after injection (i.p.) and last throughout the experiment. Alpha-LA (400 mg/kg) was appointed as the toxic dose for the BALB/c mice used in this study.The findings of the study indicate that alpha-LA at the 200 mg/kg dose show an anticonvulsant effect by reducing penicillin-induced epileptiform activity. Besides this, the delayed anticonvulsant effect of alpha-LA observed in this study gives the impression that it could result from its indirect antioxidant activity.

The involvement of iNOS activity in the anticonvulsant effect of grape seed extract on the penicillin-induced epileptiform activity in rats

Grape seed extract (GSE) has been known as being neuroprotective due to its antioxidant properties. The aim of the present study was to examine both the effect of GSE on the penicillin-induced epileptiform activity in rat and the role of nitric oxide (NO) pathway in the effect of GSE. GSE, at doses of 50, 100, 200 mg/kg, significantly decreased the mean frequency of epileptiform activity. GSE, at the highest dose (400 mg/kg), did not change either the frequency or amplitude of epileptiform activity. GSE, at a dose of 200 mg/kg, was the most effective in changing the frequency of epileptiform activity. The occurrence of anticonvulsant activity of GSE was significantly delayed in the presence of selective inducible nitric oxide synthase (iNOS) inhibitor, aminoguanidine (60 mg/kg), which was inhibited by the NO precursor, L-arginine (500 mg/kg). The administration of a non-selective NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) partially reversed the anticonvulsant activity of GSE. Selective neuronal nitric oxide synthase (nNOS) inhibitor, 7-nitroindazole (7-NI) and L-arginine showed a similar anticonvulsant activity in the presence of GSE. The electrophysiological evidence of the present study indicates that GSE decreases the mean frequency of penicillin-induced epileptiform activity, suggesting an anticonvulsant role. iNOS/NO pathway could be involved in mediating anticonvulsant effect of GSE on the epileptiform activity.

Penicillin-induced epileptiform activity elevates focal brain temperature in anesthetized rats

To elucidate a relationship between changes in focal brain temperature and severity of abnormal brain activity, epileptiform discharges and behavioral seizures were induced by Penicillin G in anesthetized rats, and focal brain-temperature was measured. Penicillin G was injected into the right primary sensorimotor cortex (400IU/μl). After the injection, epileptiform discharges induced a temperature increase gradually by 0.65±0.24°C. Moreover, when behavioral seizures were induced by reducing the anesthesia level, the temperature was raised by 0.26±0.22°C. These results suggest that elevation of the focal brain temperature is associated with the severity of epileptic activity.

The Role of CB1‐Receptors in the Proconvulsant Effect of Leptin on Penicillin‐Induced Epileptiform Activity in Rats

Prior studies have demonstrated the involvement of leptin and cannabinoids in food intake and metabolism. However, the interaction between leptin and cannabinoids in epilepsy has not been studied. This study elucidated the relationship between leptin and cannabinoids in penicillin-induced epileptiform activity in rats. The CB1 receptor agonist, arachidonyl-2-chloroethylamide (ACEA), at doses of 2.5 and 7.5 μg, the CB1 receptor antagonist, [N-(piperidine-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3 carboxamide] (AM-251), at doses of 0.125 and 0.25 μg, and leptin, at the dose of 1 μg, were administered intracerebroventricularly (i.c.v.) 30 min after intracortical penicillin (i.c.) application. Leptin caused proconvulsant activity in all groups. The administration of AM-251, at a dose of 0.25 μg, increased the frequency of penicillin-induced epileptiform activity by producing status epilepticus-like activity, whereas AM-251, at a dose of 0.125 μg, was not effective when applied alone. ACEA, at a dose of 7.5 μg, decreased the frequency of epileptiform activity. Leptin reversed the anticonvulsant activity of ACEA and enhanced the proconvulsant activity of AM-251. This study provides electrophysiological evidence that the proconvulsant activity of leptin is mediated, at least in part, by inhibition of cannabinoids in the experimental model of epilepsy.

The effect of combined treatment of alpha-tocopherol, ascorbic acid, and pyridoxine with NMDA blocker memantine on penicillin-induced epileptiform activity in rats

To evaluate the effects of coadministration of vitamins alpha-tocopherol, ascorbic acid, and pyridoxine with memantine on a penicillin-induced experimental epilepsy model in rats so as to clarify the eventual interaction between these vitamins and the N-methyl-D-aspartate (NMDA) system. Materials and methods: The epileptic focus was produced by intracortical penicillin G potassium injection. The effects of intraperitoneal injections of memantine, memantine + alpha-tocopherol, memantine + ascorbic acid, and memantine + pyridoxine combinations on epileptiform activity were evaluated in electrocorticogram recordings. Results: The antiepileptiform effects appeared earlier in all memantine and vitamin coadministrated groups compared to the memantine-alone group, but the difference between the groups was not statistically significant considering the frequency and amplitude of the epileptiform activity. Conclusion: Coadministration of vitamins does not enhance the antiepileptiform activity of memantine in penicillin-induced epilepsy in rats. However, this coadministration causes the earlier appearance of antiseizure effects. Since moderate doses of these vitamins have no side effects, it might be a good idea to use them with NMDA blockers to provide an earlier antiepileptic effect.

Chronic application of topiramate and carbamazepine differentially affects the EEG and penicillin-induced epileptiform activity in rats

Carbamazepine (CBZ) and topiramate (TPM) are among commonly used antiepileptic drugs. The acute actions of these drugs are well known but the effects of long-term use on partially induced epileptiform characteristics are yet to be clarified. The rats were received CBZ (154 mg/kg/day), TPM (10 mg/kg/day) or tap water by gavage. We investigated penicillin-induced cortical epileptiform activity and electroencephalogram spectral power of rats by using electrocorticogram recordings. Animals were anesthetized with i.p. urethane (1·25 g/kg). Analysis of electroencephalogram recordings prior to epileptiform activity revealed that 3-week treatment of CBZ significantly increased relative power of delta (P<0·01) while reduced alpha (P<0·017) and beta (P<0·017) relative power compared to both control group and TPM group. TPM had no effect on absolute power and relative power of any frequency band. TPM treatment of 21 days significantly reduced the spike frequency (P<0·01). This preventive effect was missing in CBZ-treated rats. Upon the application of the last dose of drugs during ongoing epileptiform activity, the drugs suppressed the epileptiform activity. However, TPM was more rapid and effective than CBZ. In conclusion, our in vivo electrophysiological data suggest that TPM is more effective in animal model of partial epilepsy at the applied doses in this study.

The Interactions of Nitric Oxide and Acetylcholine on Penicillin-Induced Epilepsy in Rats

The aim of this study was to investigate the interaction between nitric oxide (NO) and acetylcholine (ACh) in penicillin-induced experimental epilepsy. Adult male Wistar rats weighing 220 ± 35 g were used in the experiments. The epileptiform activity was induced by microinjection of penicillin (200 IU/1 μl) into the left sensorymotor cortex. Electrocorticogram was recorded by using Ag/AgCl ball electrodes. Sodium nitroprusside (SNP), a NO donor, given intracortically 30 min after penicillin significantly reduced the spike frequency whereas ACh increased the epileptiform activity for 5 min. Atropine, an antagonist for muscarinic receptors, was given intracortically 30 min after penicillin and did not significantly affect epileptiform activity for 30 min. SNP given after atropine significantly suppressed the epileptiform activity. ACh given 10 min after Nω-nitro-L: -arginine methyl ester (L-NAME), a nonspecific nitric oxide synthase inhibitor, did not have a significant effect on spike frequency. When ACh and SNP were administered together, penicillin induced epileptiform activity and spike frequency were significantly suppressed from the 10th minute onwards. It can be concluded that ACh increases the penicillin-induced epileptiform activity while co-administration of ACh and SNP produces a potent anticonvulsant effect as compared to SNP alone.

Central effect of crocin on penicillin-induced epileptiform activity in rats

AbstractIn the present study, the effects of separate and combined intracerebroventricular (icv) injections of crocin and diazepam were investigated on penicillin-induced epileptiform activity. In urethane-anesthetized rats, epileptiform activity was induced by intracortical (ic) administration of penicillin (200IU, 1μl) and was analyzed using electrocorticographic (ECoG) recordings. The icv injections of crocin at doses of 25, 50 and 100μg and diazepam at a dose of 10μg increased the latency time to onset of first spike wave, and decreased the frequency and amplitude of spike waves. Co-administration of an effective dose of crocin (50μg) with an ineffective dose of diazepam (2.5μg), increased the latency time to onset of first spike wave and decreased frequency and amplitude of spike waves as compared with crocin (50μg). These results indicated that crocin and diazepam produced antiepileptic activities at the levels of the brain. Crocin potentiated the antiepileptic effect of diazepam. A GABAA-benzodiazepine receptor-mediated mechanism may be involved in the antiepileptic activity of crocin.

Effect of curcumin, the active constituent of turmeric, on penicillin-induced epileptiform activity in rats.

Curcumin is a major constituent of turmeric and has many biological functions such as anticancer and anti-inflammatory effects. The present study was conducted to investigate the effects of curcumin and diazepam in separate and combined treatments on penicillin-induced seizures in rats. In urethane-anesthetized rats, epileptiform activity was induced by intracortical (i.c.) administration of penicillin (200 IU, 1 µl), and frequency and amplitude of spike waves were analyzed using electrocorticographic recordings. Intraperitoneal (i.p.) injections of curcumin at doses of 100 and 200 mg/kg, and intracerebroventricular (i.c.v.) injection of diazepam at a dose of 5 µg significantly (p<0.05) reduced both frequency and amplitude of spike waves. Co-administrations of curcumin (50 mg/kg, i.p.) with diazepam (5 µg, i.c.v) enhanced the antiepileptic effect of diazepam (5 µg, i.c.v). The results suggested that both curcumin and diazepam suppressed penicillin-induced epileptiform activity. A potentiation effect was observed between curcumin and diazepam in reducing penicillin-induced seizures.

Comparison of focally induced epileptiform activities in C57BL/6 and BALB/c mice by using in vivo EEG recording

Epilepsy characterized by repeated seizures is influenced by genetic factors. Seizure response of inbred mouse strains changes depending on the variety of stimuli including chemical (e.g., pentylenetetrazole, nicotine, cocaine, NMDA, kainate), physical (e.g., auditory) or electrical. In this study, we compared the susceptibilities of C57BL/6 and BALB/c mice strains to penicillin induced epileptiform activity (a focally induced, experimental epilepsy model), by analyzing the spike onset latency, spike amplitude and spike frequency. The power spectrums of baseline EEGs were also investigated. We found no alterations of spike onset latencies between the C57 and BALB mice. However, spike amplitudes and spike frequencies were found to be higher in BALB mice than C57 mice. With regard to EEG power spectrum, absolute power of investigated bands was not different between the two strains. Interestingly, the relative power of all investigated bands differed significantly between two strains. The relative power of delta and theta was lower whereas relative power of alpha, beta and gamma was higher in C57 mice compared to BALB mice. In conclusion, our findings showed that BALB mice are more sensitive to penicillin induced epileptiform activity when compared to C57 strain.

Penicillin induced epileptiform activity and EEG spectrum analysis of BDNF heterozygous mice: An in vivo electrophysiological study

Brain-derived neurotrophic factor (BDNF) heterozygous mice (BDNF (+/−)) kindle slowly and have a higher seizure threshold. However, BDNF (+/−) mice exhibit reduced cortical inhibition and disrupted balance of excitation/inhibition synaptic transmission. We investigated penicillin-induced focal cortical epileptiform activity and electroencephalogram (EEG) spectral power of BDNF (+/−) mice, by using electrocorticogram (ECoG) recordings. BDNF (+/−) mice (n=10) and wild type littermates (n=9) were anesthetized with i.p. urethane (1.750g/kg). The recordings of ECoG were carried out by using a data acquisition system and 100IU penicillin was administered intracortically to induce epileptiform activity. The latencies for the onset of spikes and the amplitude of the spikes showed no differences. However the frequency of the spikes was significantly lower in BDNF (+/−) mice at 40th and 45thmin following penicillin injection. Additionally, the EEG power for both BDNF (+/−) and wild type mice reduced after penicillin injection and enhanced during epileptiform activity. The spectral power analysis also revealed that the absolute Gamma power of BDNF (+/−) was significantly smaller than wild types.The results of the present study provide the first in vivo electrophysiological evidence that BDNF heterozygous mice exhibited suppressed epileptiform activity. Moreover, reduced levels of BDNF led to a reduction of absolute Gamma band power.

The interactions of nitric oxide and adenosine on penicillin-induced epileptiform activity in rats.

In this study, the influence of nitric oxide (NO) and adenosine systems on penicillin-induced epileptiform activity was examined in rats. NO donor, sodium nitroprusside (SNP, 50 micrograms per rat, i.c.v.) reduced the frequency but not the amplitude of epileptiform discharges. Non-selective NOS inhibitor, N-omega-nitro-L-arginine methyl ester (L-NAME, 100 micrograms per rat, i.c.v.) practically did not exert any effect on the spike frequency and amplitude. Adenosine (100 micrograms per rat, i.c.) reduced spike frequency but not the amplitude, whereas theophylline (100 micrograms per rat, i.c.v.) increased the mean spike frequency and amplitude of penicillin-induced epileptiform discharges. Co-injection of theophylline and L-NAME did not cause a further increase in the epileptiform activity compared with theophylline. When NO production was blocked with L-NAME, the inhibitory effects of adenosine were lost. The obtained results suggest that NO and adenosine may decrease penicillin-induced epileptiform activity in rats and that NO, at least in part, may mediate the anticonvulsant effect of adenosine.

Short-duration swimming exercise decreases penicillin-induced epileptiform ECoG activity in rats.

The aim of the present study is to understand the basic relationship between swimming exercise and natural course of epilepsy in animals by performing an electrophysiological study. For this purpose, male Wistar rats were submitted to daily swimming exercise program of three different durations. Animals were swim-exercised for 90 days with either 15 minutes, 30 minutes or 60 minutes/day. Thereafter, the epileptiform activity was induced by a single microinjection of penicillin (500 units) into the left somatomotor cortex. Short-duration swimming exercise (15 min per day for 90 days) decreased the mean frequency and amplitude of penicillin-induced epileptiform activity in the 70 and 90 minutes after penicillin injection compared to penicillin administered group, respectively. Moderate-duration (30 min per day for 90 days) and long-duration (60 min per day for 90 days) swimming exercise did not alter either the frequency or amplitude of epileptiform activity. The results of the present study provide electrophysiologic evidence that short-duration swimming exercise partially inhibits penicillin-induced epileptiform activity. These data also suggest that moderate and long-duration swimming exercise do not increase either the frequency or severity of seizure in the model of penicillin-induced epilepsy.

The effect of co-administration of the NMDA blocker with agonist and antagonist of CB1-receptor on penicillin-induced epileptiform activity in rats

Although the activation of CB1-receptor by cannabinoids and block of NMDA receptors are known to decrease seizure severity in epilepsy models, the interaction between these systems remain elusive. Therefore, the present study was initiated to evaluate the possible interactions between cannabinoid compounds and NMDA receptor antagonist in the penicillin-induced epileptiform activity in rat. In the first set of experiments, 30 min after intracortical injection of penicillin, five different doses of memantine (3,5-dimethyl-1-adamantanamine hydrochloride, 1, 2.5, 5, 10 or 20mg/kg) were administered intraperitoneally (i.p.). In the second set of experiments, intracerebroventricular (i.c.v.) AM-251 [N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide], (0.25 μg) a CB1-receptor antagonist and ACEA (arachidonyl-2-chloroethylamide), (7.5 μg) a CB1-receptor agonist, were administered 15 min after memantine (i.p.) application. Memantine, NMDA receptor antagonist, at doses of 2.5 and 5mg/kg (i.p.) decreased the mean frequency of penicillin-induced epileptiform activity with a maximal effect at 5mg/kg. Memantine, at the lowest dose (1mg/kg, i.p.) and highest doses (10 and 20mg/kg, i.p.) did not change the frequency of epileptiform activity. ACEA, at a dose of 7.5 μg, also decreased the frequency of epileptiform activity, whereas AM-251, at a dose of 0.25 μg increased the frequency by causing status epilepticus-like activity. The best and earlier anti-epileptiform effects appeared in both the presence of memantine (5mg/kg, i.p.) and ACEA (7.5 μg, i.c.v.), which was blocked by CB1-receptor antagonist, AM-251. The results of the present study provide electrophysiologic evidence for an interaction between cannabinoid system and NMDA receptors, probably via NMDA-mediated Ca(2+) influx in the penicillin-induced epilepsy.